| 301 | Citrus Energy Corporation | Castle Rock, CO 80104 | Oil & Gas Operator | Mar 2020 |
| 302 | Civic Energy Corporation | Colony, OK 73021 | Oil & Gas Operator | Jan 2025 |
| 303 | CK Resources | Cleveland, OK 74020-0772 | Oil Operator | Aug 2013 |
| 304 | Claassen Oil And Gas, Inc. | Estes Park, CO 80517 | Oil & Gas Operator | Dec 2024 |
| 305 | Claborn Julia | Okmulgee, OK 74447-9781 | Oil & Gas Operator | Mar 2022 |
| 306 | Claiborne-McDonald Inc | Chickasha, OK 73018 | Oil Operator | Jul 2007 |
| 307 | Clapp Carl O | Cedar Vale, KS 67024 | Oil Operator | Aug 2013 |
| 308 | Claremont Corporation | Tulsa, OK 74119 | Oil & Gas Operator | Feb 2017 |
| 309 | Claremont Exploration Inc | Tulsa, OK 74103-4107 | Oil & Gas Operator | Jun 1997 |
| 310 | Clarita Operating LLC | Ada, OK 74821 | Oil Operator | Jun 2022 |
| 311 | Clark And Clark | Princeton, NJ 08540-1930 | Oil & Gas Operator | Jul 2013 |
| 312 | Clark Exploration Co. | Highlands Ranch, CO 80126-7645 | Oil & Gas Operator | Nov 2024 |
| 313 | Clark Krista | Ada, OK 74820-8595 | Oil Operator | Sep 2001 |
| 314 | Clark Operating Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Apr 2025 |
| 315 | Clark Operating Services, Inc. | Okmulgee, OK 74447 | Oil & Gas Operator | May 2013 |
| 316 | Clark Well Service | Depew, OK 74028-0296 | Oil & Gas Operator | Aug 2013 |
| 317 | Class Petroleum Corporation | Barnsdall, OK 74002 | Oil Operator | Aug 2013 |
| 318 | Clay Investments LLC | Stillwater, OK 74075-3600 | Oil & Gas Operator | Jan 2021 |
| 319 | Claybrook Drilling Co Inc | | Oil & Gas Operator | Sep 2014 |
| 320 | Claybrook Production Co. Inc. | Wewoka, OK 74884-1380 | Oil & Gas Operator | Jun 2014 |
| 321 | Clayton Corp Petro & Natural Gas Prod | Lakewood, CO 80228-1836 | Oil & Gas Operator | Oct 2020 |
| 322 | Clayton Corporation | Golden, CO 80401 | Oil & Gas Operator | Dec 2019 |
| 323 | CLC Operations Inc | Midland, TX 79701 | Oil & Gas Operator | Mar 1997 |
| 324 | Clean Oil LLC | Ada, OK 74820 | Oil & Gas Operator | Jan 2025 |
| 325 | Clear Creek Royalty LLC | Tulsa, OK 74137 | Oil & Gas Operator | Jul 2023 |
| 326 | Cleary Exploration LLC | Oklahoma City, OK 73112-7221 | Oil & Gas Operator | Oct 2014 |
| 327 | Cleary Jo Anne | Saint Louis, OK 74866 | Oil Operator | Jan 2025 |
| 328 | Cleary Petroleum Corporation | Edmond, OK 73083 | Oil & Gas Operator | Jul 2019 |
| 329 | Cleere Operating LLC | Shawnee, OK 74804-2610 | Oil Operator | Dec 2024 |
| 330 | Clements Exploration Co | Oklahoma City, OK 73132-5922 | Oil & Gas Operator | Jan 2006 |
| 331 | Clemishire Bryan | Hominy, OK 74035 | Oil & Gas Operator | Nov 2014 |
| 332 | Clemishire Don | Hominy, OK 74035 | Oil & Gas Operator | Jan 2025 |
| 333 | Clemishire Mark | Hominy, OK 74035 | Oil Operator | Jan 2025 |
| 334 | Clemishire, Jerry L | | Oil & Gas Operator | Jan 2025 |
| 335 | Clemshire Bob | Hominy, OK 74035 | Oil & Gas Operator | Jan 2025 |
| 336 | Clemshire Drilling Company | Tulsa, OK 74105 | Oil Operator | Jan 2025 |
| 337 | Cleveland Rod & Tracy | Elmore City, OK 73433-9467 | Oil & Gas Operator | Jul 2023 |
| 338 | Click Betty | Stigler, OK 74462-0081 | Oil & Gas Operator | Feb 2016 |
| 339 | Click Robert R | Dallas, TX 75231 | Oil & Gas Operator | Nov 1995 |
| 340 | Clifford Resources Inc | Oklahoma City, OK 73120 | Oil & Gas Operator | Jul 2015 |
| 341 | Cliffwood Production Co. | Houston, TX 77090 | Oil & Gas Operator | Aug 2013 |
| 342 | Clift Cary E | Chickasha, OK 73018-6305 | Oil & Gas Operator | Sep 2024 |
| 343 | Clifton & Associates Inc | Tulsa, OK 74133 | Oil & Gas Operator | May 2020 |
| 344 | Clifton Consulting Inc | Piedmont, OK 73078-0180 | Gas Operator | Jan 2025 |
| 345 | Clindco Inc | Bartlesville, OK 74006-6213 | Oil & Gas Operator | Oct 2019 |
| 346 | Cline Oil And Gas Company | Santa Fe, NM 87501 | Oil & Gas Operator | Sep 1994 |
| 347 | Clinton Public Works Authority | Clinton, OK 73601 | Oil & Gas Operator | May 2023 |
| 348 | CLM Oil Production Inc | Bartlesville, OK 74006-4417 | Oil & Gas Operator | Jan 2025 |
| 349 | Cloer VIrgil R | Oklahoma City, OK 73121 | Oil & Gas Operator | Apr 1993 |
| 350 | CLV Oil & Gas Inc | Tulsa, OK 74169-0713 | Oil & Gas Operator | Apr 2020 |
| 351 | Clydesdale Energy LLC | Oklahoma City, OK 73116-9111 | Oil & Gas Operator | Nov 2019 |
| 352 | CM Exploration Company Inc. | | Oil & Gas Operator | Apr 2009 |
| 353 | CM Oil Co. | FT Stockton, TX 79735 | Oil & Gas Operator | Apr 2025 |
| 354 | Cmint Productions LLC | Dallas, TX 75248-2643 | Oil Operator | Oct 2021 |
| 355 | Cmo LLC | Cleveland, OK 74020 | Oil & Gas Operator | Jan 2025 |
| 356 | CMR Operating LLC | Tulsa, OK 74135-2653 | Oil & Gas Operator | Jun 2018 |
| 357 | CMS Energy Inc | Dallas, TX 75287 | Oil & Gas Operator | Jan 2025 |
| 358 | CMS Nomeco Oil & Gas Co. | Jackson, MI 49201 | Oil & Gas Operator | Jan 2015 |
| 359 | CMT Oil & Gas Company Inc | Tulsa, OK 74133-6724 | Oil & Gas Operator | Jan 2025 |
| 360 | CMT Operating LLC | Cleveland, OK 74020-0113 | Oil & Gas Operator | Mar 2015 |
| 361 | CMX Inc Of Kansas | Wichita, KS 67206-2561 | Oil & Gas Operator | Feb 2025 |
| 362 | CN Operating Company | Drumright, OK 74030 | Oil & Gas Operator | Nov 1998 |
| 363 | CNR Resources, Inc. | Houston, TX 77002-4103 | Oil & Gas Operator | May 2005 |
| 364 | Co-St Oil Operating Co Inc | Enid, OK 73706 | Oil & Gas Operator | Apr 1997 |
| 365 | Coal Oil & Gas Company | Ada, OK 74820 | Oil & Gas Operator | Feb 2025 |
| 366 | Coaleum Corporation | Dallas, TX 75205 | Oil & Gas Operator | Jan 2001 |
| 367 | Coalinga Corporation | Houston, TX 77002 | Oil & Gas Operator | May 1999 |
| 368 | Coast David | Bartlesville, OK 74006-0407 | Oil & Gas Operator | Jan 2025 |
| 369 | Coast Petroleum Company | | Oil Operator | Nov 1998 |
| 370 | Coastal Derby Refining Co | Houston, TX 77046 | Oil Operator | Feb 1994 |
| 371 | Coastal Oil & Gas Corporation | Houston, TX 77252 | Oil & Gas Operator | Dec 2009 |
| 372 | Coastal Oils Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Jan 2013 |
| 373 | Coastal Plains Energy Inc | Oklahoma City, OK 73112 | Oil & Gas Operator | Apr 2025 |
| 374 | Coastal States Gas Prod. Co. | | Oil & Gas Operator | Jun 1996 |
| 375 | Cobalt Environmental Solutions LLC | Oklahoma City, OK 73101-0249 | Oil Operator | Jun 2019 |
| 376 | Cobopco Inc | Tulsa, OK 74103-4391 | Oil & Gas Operator | Feb 1997 |
| 377 | Cobra Oil & Gas Corporation | Wichita Falls, TX 76307 | Oil & Gas Operator | Apr 2025 |
| 378 | Cochran Industrial Corporation | Cushing, OK 74023-1427 | Oil & Gas Operator | Apr 2001 |
| 379 | Cochran T H & Edna | | Oil Operator | Jan 1996 |
| 380 | Coe Production Company | Talala, OK 74080-0264 | Oil & Gas Operator | Aug 2015 |
| 381 | Coe Production Company LLC | Talala, OK 74080 | Oil Operator | Jan 2025 |
| 382 | Coenergy Operating Company | Oklahoma City, OK 73112 | Oil & Gas Operator | Mar 2015 |
| 383 | COG Petroleum Corporation | Oklahoma City, OK 73116-7326 | Oil & Gas Operator | Mar 2019 |
| 384 | Cogburn Oil Co Inc | | Oil & Gas Operator | Sep 2023 |
| 385 | Coho Oil & Gas Inc | Coppell, TX 75019-8288 | Oil & Gas Operator | Mar 2015 |
| 386 | Coker Oil Company | Duncan, OK 73533-0818 | Oil Operator | Jan 2014 |
| 387 | Cola Resources LLC | Houston, TX 77019-5639 | Gas Operator | Nov 2015 |
| 388 | Coldren Oil & Gas Inc | Bartlesville, OK 74006-4729 | Oil & Gas Operator | Sep 1998 |
| 389 | Coleman Oil Company | Bartlesville, OK 74003 | Oil Operator | Dec 2023 |
| 390 | Coleman Oil LLC | Marlow, OK 73055 | Oil Operator | Nov 2021 |
| 391 | Coleman Production | Stroud, OK 74079-9609 | Oil & Gas Operator | May 2013 |
| 392 | Collet Oil Ventures, Inc. | Denver, CO 80217 | Oil & Gas Operator | Jun 2004 |
| 393 | Collier Petroleum Corporation | Taloga, OK 73667-9644 | Oil & Gas Operator | Jan 2013 |
| 394 | Collins Dillard Dba Dilco Oil Company | Mangum, OK 73554-4029 | Oil & Gas Operator | Mar 2024 |
| 395 | Collins Oil & Gas | Bartlesville, OK 74006 | Oil Operator | Jan 2025 |
| 396 | Collins Petroleum Inc | Bartlesville, OK 74006-7024 | Oil & Gas Operator | Apr 2005 |
| 397 | Colonial Energy Company Inc | Garland, TN 75045 | Oil & Gas Operator | Apr 2015 |
| 398 | Colonial Resources LLC | Edmond, OK 73003-3207 | Oil & Gas Operator | Aug 2019 |
| 399 | Colorado Gas Compression Inc | Longmont, CO 80501-5868 | Oil & Gas Operator | Aug 2013 |
| 400 | Colorado Interstate Gas Co | Colorado Springs, CO 80944 | Oil & Gas Operator | Jul 2004 |